A South Korean soldier who killed five members of his own unit was humiliated by comrades who drew pictures of him as SpongeBob SquarePants, according to military officials.

The soldier, known only as Sergeant Lim, killed five and wounded seven others during the rampage in June.

He then went on the run with his rifle and several rounds of ammunition before being caught two days later following a stand off and failed suicide attempt.

Lim had been repeatedly mocked by lower and higher-ranking members of his unit, senior military investigator Seon Jong-Chul found following a probe into the tragedy.

Sketches drawn on the back pages of the unit’s daily border patrol logs, depicting Lim as a number of cartoon characters, including SpongeBob, on the day of the shootings made him particularly angry it has been reported.

“Other troops saw it as a small joke, but (Lim) said he had been greatly distressed by it,” Seon said, adding that the cartoons had “triggered a flashback” to when Lim was bullied in high school.

Although other soldiers in the unit were also caricatured in the log book, Lim took the cartoons of him personally, according to the news agency Agence France-Presse.

Lim had joined the army in 2012 and was due to be discharged three months before his killing spree. But he had difficulty adapting to the army and psychological evaluations had advised senior officials to pay special attention to him.

The killings took place at his base in Goseong county, which borders North Korea.

Lim's victims were believed to be a staff sergeant, a sergeant, a corporal and two privates.

Helicopters were used to scour the hillside for him before tracking him down near a school. Lim's parents were taken to the site, where his mother begged him to give himself up.

Lim was formally arrested earlier this month, after being treated for a self inflicted gunshot wound, on charges including murder, attempted murder, and stealing military equipment.

In a note written before he was arrested, released by the military today, Lim said: “Anybody would have felt that life was more painful and difficult than death if they were in my shoes.

“Like little children who kill insects without feeling guilty ... they do not know how much pain they can give to someone."

Six surviving members of Lim’s unit are alleged to have taken part in the bullying and would face disciplinary punishment, according to AFP, while Lim has filed a lawsuit against a senior officer for insulting behaviour.